Having to, potentially, interact with a stranger who has their breasts (which, for most people, are a rather private part of their body) hanging out is something that I can only imagine to be greatly discomfiting and embarrassing for a great many people. It most certainly is not something that harms nobody.
Explain.
Well, it physically harms no-one, other than the proverbial guy who gets distracted (as we men, regrettably, do) and walks into a lamp post or crashes his car. However, if we apply a broad definition of harm to include discomfiture, then having these, ah, items on display most certainly will cause discomfiture and embarrassment for many, and thus harm.'If it makes me uncomfortable, it is harming me. Ergo, it should be prohibited.'
What kind of 'logic' is that? A lot of things in life makes me uncomfortable (i.e. gay male couples holding hands and kissing), yet I don't go out of my way to prohibit the act.
Do tell.